Ethylene Copolymers, Methods for Their Production, and Use

ABSTRACT

Provided is an ethylene copolymer having 40 wt. % to 70 wt. % of units derived from ethylene and at least 30 wt. % of units derived from at least one α-olefin having 3 to 20 carbon atoms and has the following properties:
         (a) a weight-average molecular weight (Mw), as measured by GPC, in the range of about 50,000 to about 200,000 g/mol;   (b) a melting point (Tm) in ° C., as measured by DSC, that satisfies the relation:       

         Tm &gt;3.4× E −180
 
     where E is the weight % of units derived from ethylene in the copolymer;
         (c) a ratio of Mw/Mn of about 1.8 to about 2.5;   (d) a content of Group 4 metals of no more than 5 ppm; and   (e) a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of at least 3.       

     Also provided are methods for making an ethylene copolymer and compositions comprising an ethylene copolymer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 61/297,621 (2010EM012), filed Jan. 22, 2010 and U.S.Provisional Application No. 61/368,997 (2010EM200), filed Jul. 29, 2010.This application is related to U.S. patent application Ser. No.12/761,880 (2009EM079/2), filed Apr. 16, 2010; U.S. patent applicationSer. No. 12/762,096 (2009EM082/2), filed Apr. 16, 2010; U.S. patentapplication Ser. No. 12/569,009 (2009EM210), filed Sep. 29, 2009; andInternational Patent Application No. PCT/US2010/031190 (2009EM210),filed Apr. 15, 2010 each of which in turn claims priority to ProvisionalApplication No. 61/173,528 (2009EM079), filed Apr. 28, 2009 andProvisional Application No. 61/173,501 (2009EM082), filed Apr. 28, 2009,the disclosures of which are incorporated by reference in theirentireties.

FIELD OF THE INVENTION

The present invention relates to ethylene copolymers, their productionand their use, particularly as viscosity modifiers for lubricating oils.

BACKGROUND OF THE INVENTION

Ethylene copolymers, especially copolymers of ethylene with propyleneoptionally in combination with non-conjugated diolefins, are widely usedas thermoplastic polymers, as elastomeric polymers in both vulcanizedand unvulcanized compositions, in blends and as viscosity modifiers inlubricating oil formulations. One example of the use of these materialsas viscosity modifiers is disclosed in U.S. Pat. No. 6,589,920.

The elastomeric properties of ethylene copolymers depend largely on theethylene content of the copolymer since materials with higher ethylenecontents have a lower entanglement molecular weight. The solutionproperties also depend to a large extent on the ethylene content; with alow ethylene content EP copolymer being desirable when the copolymer isintended for use as a viscosity modifier for waxy base stock oilsbecause this provides excellent low temperature properties whilemaintaining good thickening efficiency. In addition, for manyapplications, low molecular weight EP copolymers are needed, for exampleto meet shear stability standards when used in motor oil formulations.

However, EP copolymers with low ethylene content, e.g., 40 to 55 weightpercent (wt. %) ethylene, and low molecular weight, e.g., below 100,000g/mol, are currently very difficult to produce and handle, particularlyusing most metallocene catalysts systems. Thus, these materials tend tobe amorphous and have a propensity to agglomerate or cold flow and stickto finishing equipment.

Ethylene copolymers having a high ethylene content, e.g., ranging from70 wt. % to 90 wt. %, are also desirable because of their outstandinglow temperature impact strength due to low crystallinity, low modulus,and high flexibility. Furthermore, metallocene based EP copolymers withethylene contents ranging from 70 wt. % to 90 wt. % show very goodorganoleptics, i.e., low odor/taste/extractables, due to their narrowmolecular weight distribution as compared to Ziegler/Natta basedcopolymers. However, these copolymers are also difficult to handle andmay have an unacceptably low service temperatures due to the inherentlylow melting point of the random copolymers produced using mostmetallocene-based and Ziegler/Natta-based catalyst systems.

There is therefore, a need for ethylene copolymers having both a lowethylene content and a low molecular weight that can be handled inconventional processing equipment without the problem of agglomerationduring finishing, packaging and transportation. In addition, there is aneed for ethylene copolymers that have a high ethylene content incombination with a low molecular weight and that exhibit an improvedmelting point without loss of their low temperature properties.

SUMMARY OF THE INVENTION

It has now been found, by using a particular metallocene catalystsystem, it is possible to produce a low molecular weight ethylenecopolymer that has sufficient crystallinity to reduce agglomerationproblems at low ethylene contents and to increase melting point at highethylene contents, both without adversely affecting the low temperatureproperties of the copolymer.

In one aspect, provided is an ethylene copolymer comprising 40 wt. % to70 wt. % of units derived from ethylene and at least 30 wt. % of unitsderived from at least one α-olefin having 3 to 20 carbon atoms, whereinthe copolymer has the following properties:

(a) a weight-average molecular weight (Mw), as measured by gelpermeation chromatography (GPC), in the range of about 50,000 to about200,000 g/mol;

(b) a melting point (Tm) in ° C., as measured by differential scanningcalorimetry (DSC), that satisfies the relation:

Tm>3.4×E−180

where E is the weight % of units derived from ethylene in the copolymer;

(c) a ratio of Mw/Mn of about 1.8 to about 2.5;

(d) a content of Group 4 metals of no more than 5 ppm; and

(e) a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of at least3.

In some embodiments, said copolymer comprises 40 wt. % to 55 wt. % ofunits derived from ethylene and 60 wt. % to 45 wt. % of units derivedfrom units derived from at least one α-olefin having 3 to 20 carbonatoms.

In some embodiments, the copolymer has a melting point (Tm) in ° C., asmeasured by DSC, that satisfies the relation: Tm>3.4×E−170, or therelation: Tm>3.4×E−160, or the relation: Tm>3.4×E−90, where E is asdefined above.

In a further aspect, provided is an ethylene copolymer comprising 70 wt.% to 85 wt. % of units derived from ethylene and at least 12 wt. % ofunits derived from at least one α-olefin having 3 to 20 carbon atoms,wherein the copolymer has the following properties:

(a) a weight-average molecular weight (Mw), as measured by GPC, in therange of about 50,000 to about 200,000 g/mol;

(b) a melting point (Tm), as measured by DSC, of at least 100° C., suchas at least 110° C.;

(c) a ratio of Mw/Mn of about 1.8 to about 2.5;

(d) a content of Group 4 metals of no more than 5 ppm; and

(e) a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of at least3.

In some embodiments, said at least one α-olefin is selected frompropylene, butene, hexene and octene, especially propylene.

In some embodiments, the copolymer contains no more than 25 ppm of Zn.

In another aspect, provided is a process of producing an ethylenecopolymer, the process comprising contacting a monomer mixturecomprising 40 wt. % to 70 wt. % of ethylene and at least 30 wt. % of atleast one α-olefin having 3 to 20 carbon atoms under polymerizationsconditions with a catalyst composition comprising a bridged bis-indenylcomplex of a transition metal to produce a copolymer having thefollowing properties:

(a) a weight-average molecular weight (Mw), as measured by GPC, in therange of about 50,000 to about 200,000 g/mol;

(b) a melting point (Tm) in ° C., as measured by DSC, that satisfies therelation:

Tm>3.4×E−180

where E is the weight % of units derived from ethylene in the copolymer;

(c) a ratio of Mw/Mn of about 1.8 to about 2.5;

(d) a content of Group 4 metals of no more than 5 ppm; and

(e) a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of at least3.

In yet another aspect, provided is a process of producing an ethylenecopolymer, the process comprising contacting a monomer mixturecomprising 70 wt. % to 85 wt. % of ethylene and at least 12 wt. % of atleast one α-olefin having 3 to 20 carbon atoms under polymerizationsconditions with a catalyst composition comprising a bridged bis-indenylcomplex of a transition metal to produce a copolymer having thefollowing properties:

(a) a weight-average molecular weight (Mw), as measured by GPC, in therange of about 50,000 to about 200,000 g/mol;

(b) a melting point (Tm), as measured by DSC, of at least 100° C., suchas at least 110° C.;

(c) a ratio of Mw/Mn of about 1.8 to about 2.5;

(d) a content of Group 4 metals of no more than 5 ppm; and

(e) a ratio of ppm Group 4 metals/ppm Group 5 metals of at least 3.

In some embodiments, the bridged bis-indenyl complex comprises adialkylsilyl bridging group and the transition metal comprises hafniumand/or zirconium.

In some embodiments, the catalyst composition comprisesdimethylsilylbisindenylhafnium dimethyl.

In some embodiments, the catalyst composition comprises afluoroarylborate activator and especially a perfluoroarylborateactivator.

In still a further aspect, provided is a lubricating oil compositioncomprising: (a) a lubricating oil base; and (b) an ethylene copolymer asdescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph illustrating peak melting point against ethylenecontent for the ethylene copolymers of the present invention andExamples 6 to 8 of U.S. Pat. No. 6,589,920.

DETAILED DESCRIPTION

Described herein is a range of ethylene-containing copolymers whichexhibit low levels of crystallinity, while unexpectedly having unusuallyhigh melting points, over a wide range of ethylene concentrations. Alsodescribed are methods of producing these copolymers using ametallocene-based catalyst systems and use of the copolymers asviscosity modifiers for lubricating oils.

Ethylene Copolymer

As used herein the term “copolymer” is any polymer produced from two ormore different monomers. In the present copolymers, the monomersemployed comprise ethylene and one or more α-olefins having 3 to 20carbon atoms. Suitable α-olefin comonomers include propylene; 1-butene;3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with oneor more methyl, ethyl or propyl substituents; 1-hexene with one or moremethyl, ethyl or propyl substituents; 1-heptene with one or more methyl,ethyl or propyl substituents; 1-octene with one or more methyl, ethyl orpropyl substituents; 1-nonene with one or more methyl, ethyl or propylsubstituents; ethyl, methyl or dimethyl-substituted 1-decene, and1-dodecene. Generally, the α-olefin comonomer is selected frompropylene, butene, hexene and octene, with propylene being preferred.

The present copolymers exhibit at least one of the following properties:

-   -   (i) a weight-average molecular weight (Mw), as measured by gel        permeation chromatography (GPC), in the range of about 25,000 to        about 500,000, or from about 40,000 to about 300,000 or from        about 50,000 to about 200,000 g/mol;    -   (ii) a molecular weight distribution (MWD), defined as the ratio        of the weight average molecular weight (Mw) to the number        average molecular weight (Mn), of from about 1.5 to about 4.0 or        from about 1.5 to about 3.5, or from about 1.5 to about 3.0, or        from about 1.8 to about 3.0, or from about 1.8 to about 2.8, or        from about 1.8 to about 2.5;    -   (iii) since the present copolymers are produced using a        metallocene-based, rather than a Ziegler Natta, catalyst system        they contain very low amounts of Group 4 metals. Preferably, the        copolymers include less than 0.5 wt. % of Group 4 metals. More        preferably, the copolymers are substantially free of Group 4        metals. In one or more embodiments, the copolymers include no        more than about 100 ppm or no more than about 50 ppm or no more        than about 25 ppm or no more than about 15 ppm or no more than        about 10 ppm or no more than about 5 ppm of Group 4 metals;    -   (iv) a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of        at least 1, or at least 2, or at least 3, or at least 4;    -   (v) since the present copolymers can be produced without using a        chain shuttling polymerization process, such as disclosed in        U.S. Patent Application Publication No. 2007/0167315, the        copolymers typically contain no more than 100 ppm, or no more        than 50 ppm, or no more than 25 ppm, or no more than 10 ppm, or        no more than 5 ppm of Zn; and    -   (vi) combinations of properties (i)-(v) described above.

The presence of Group 4 and Group 5 metals and/or zinc in the polymermay be measured using Inductively Coupled Plasma Atomic EmissionSpectroscopy (ICP-AES); a technique that is commonly known in the art.For ICP-AES measurements, the samples to be measured are first ashed,then dissolved in an appropriate acidic solution, followed byappropriate dilution to fall within the standard calibration curve. Asuitable instrument is the IRIS ADVANTAGE DUAL VIEW instrumentmanufactured by Thermo Electron Corporation (Now Thermo FisherScientific Inc., 81 Wyman Street Waltham, Mass. 02454).

In one or more embodiments, the present copolymers comprise 40 wt. % to70 wt. %, more typically 40 wt. % to 55 wt. %, of units derived fromethylene and at least 30 wt. %, more typically 60 wt. % to 45 wt. %, ofunits derived from at least one α-olefin having 3 to 20 carbon atoms.Even with such a relatively low ethylene content, the copolymers have amelting point (Tm) in ° C., as measured by differential scanningcalorimetry (DSC), that satisfies the relation:

Tm>3.4×E−180

where E is the weight % of units derived from ethylene in the copolymerso that, for example, with a copolymer containing 55 wt. % ethylene, theTm is greater than 7° C. In certain cases, the copolymers of the firstembodiment have a melting point (Tm) in ° C., as measured by DSC, thatsatisfies the relation: Tm>3.4×E−170, or the relation: Tm>3.4×E−160, orthe relation: Tm>3.4×E−90, where E is as defined above.

In another embodiment, the present copolymers comprise 70 to 85 wt. % ofunits derived from ethylene and at least 12 wt. % of units derived fromat least one α-olefin having 3 to 20 carbon atoms. In this case, thecopolymers have a melting point (Tm), as measured by DSC, of at least100° C., more typically at least 110° C.

Metallocene Catalyst System

The metallocene catalyst system employed to produce the present ethylenecopolymers comprises: (i) a complex of a transition metal, oftenreferred to as a metallocene, metallocene catalyst precursor, orcatalyst precursor; and (ii) an activator.

Metallocenes

The metallocene compounds useful herein are generally known in the art,and are preferably cyclopentadienyl derivatives of titanium, zirconiumand hafnium. Useful metallocenes (e.g. titanocenes, zirconocenes andhafnocenes) may be represented by the following formulae:

wherein M is the metal center, and is a Group 4 metal, preferablytitanium, zirconium or hafnium, preferably zirconium or hafnium when L₁and L₂ are present and preferably titanium when Z is present; n is 0 or1;T is an optional bridging group which, if present, in preferredembodiments is selected from dialkylsilyl, diarylsilyl, dialkylmethyl,ethylenyl (—CH₂—CH₂—) or hydrocarbylethylenyl wherein one, two, three orfour of the hydrogen atoms in ethylenyl are substituted by hydrocarbyl,where hydrocarbyl can be independently C₁ to C₁₆ alkyl or phenyl, tolyl,xylyl and the like, and when T is present, the catalyst represented canbe in a racemic or a meso form;L₁ and L₂ are the same or different cyclopentadienyl, indenyl,tetrahydroindenyl or fluorenyl rings, optionally substituted, that areeach bonded to M, or L₁ and L₂ are the same or differentcyclopentadienyl, indenyl, tetrahydroindenyl or fluorenyl, which areoptionally substituted, in which any two adjacent R groups on theserings are optionally joined to form a substituted or unsubstituted,saturated, partially unsaturated, or aromatic cyclic or polycyclicsubstituent;Z is nitrogen, oxygen or phosphorus (preferably nitrogen);R′ is a cyclic linear or branched C₁ to C₄₀ alkyl or substituted alkylgroup (preferably Z—R′ form a cyclododecylamido group); andX₁ and X₂ are, independently, hydrogen, halogen, hydride radicals,hydrocarbyl radicals, substituted hydrocarbyl radicals, halocarbylradicals, substituted halocarbyl radicals, silylcarbyl radicals,substituted silylcarbyl radicals, germylcarbyl radicals, or substitutedgermylcarbyl radicals; or both X are joined and bound to the metal atomto form a metallacycle ring containing from about 3 to about 20 carbonatoms; or both together can be an olefin, diolefin or aryne ligand.

By use of the term hafnocene is meant a bridged or unbridged, bis- ormono-cyclopentadienyl (Cp) hafnium complex having at least two leavinggroups X₁ and X₂, which are as defined immediately above and where theCp groups may be substituted or unsubstituted cyclopentadiene, indene orfluorene. By use of the term zirconocene is meant a bridged orunbridged, bis- or mono-Cp zirconium complex having at least two leavinggroups X₁ and X₂, which are as defined immediately above and where theCp groups may be substituted or unsubstituted cyclopentadiene, indene orfluorene. By use of the term titanocene is meant a bridged or unbridged,bis- or mono-Cp titanium complex having at least two leaving groups X₁and X₂, which are as defined immediately above and where the Cp groupsmay be substituted or unsubstituted cyclopentadiene, indene or fluorene.

Among the metallocene compounds which can be used in this invention arestereorigid, chiral or asymmetric, bridged or non-bridged, or so-called“constrained geometry” metallocenes. See, for example, U.S. Pat. No.4,892,851; U.S. Pat. No. 5,017,714; U.S. Pat. No. 5,132,281; U.S. Pat.No. 5,155,080; U.S. Pat. No. 5,296,434; U.S. Pat. No. 5,278,264; U.S.Pat. No. 5,318,935; U.S. Pat. No. 5,969,070; U.S. Pat. No. 6,376,409;U.S. Pat. No. 6,380,120; U.S. Pat. No. 6,376,412; WO-A-(PCT/US92/10066);WO 99/07788; WO-A-93/19103; WO 01/48034; EP-A2-0 577 581; EP-A1-0 578838; WO 99/29743 and also the academic literature, see e.g., “TheInfluence of Aromatic Substituents on the Polymerization Behavior ofBridged Zirconocene Catalysts,” Spaleck, W. et al, Organometallics 1994,Vol. 13, pp. 954-963, and “ansa-Zirconocene Polymerization Catalystswith Annelated Ring Ligands-Effects on Catalytic Activity and PolymerChain Lengths,” Brintzinger, H. et al, Organometallics 1994, Vol. 13,pp. 964-970, and documents referred to therein. The bridged metallocenesdisclosed in WO 99/07788 and the unbridged metallocenes disclosed inU.S. Pat. No. 5,969,070 are particularly suitable for the presentinvention.

Preferably, the transition metal compound is a dimethylsilylbis(indenyl)metallocene, wherein the metal is a Group 4 metal, specifically,titanium, zirconium, or hafnium, and the indenyl may be substituted byone or more substituents selected from the group consisting of a halogenatom, C₁ to C₁₀ alkyl, C₅ to C₁₅ aryl, C₆ to C₂₅ arylalkyl, and C₆ toC₂₅ alkylaryl. More preferably, the metal is zirconium or hafnium, L₁and L₂ are unsubstituted or substituted indenyl radicals, T isdialkylsiladiyl, and X₁ and X₂ are both halogen or C₁ to C₃ alkyl.Preferably, these compounds are in the rac-form.

Illustrative, but not limiting examples of preferred stereospecificmetallocene compounds are the racemic isomers ofdimethylsilylbis(indenyl) metal dichloride, -diethyl or -dimethyl,wherein the metal is titanium, zirconium or hafnium, preferably hafniumor zirconium. It is particularly preferred that the indenyl radicals arenot substituted by any further substituents. However, in certainembodiments the two indenyl groups may also be replaced, independentlyof each other, by 2-methyl-4-phenylindenyl; 2-methyl indenyl; 2-methyl,4-[3′,5′-di-t-butylphenyl]indenyl;2-ethyl-4-[3′,5′-di-t-butylphenyl]indenyl;2-n-propyl-4-[3′,5′-di-t-butylphenyl]indenyl;2-iso-propyl-4-[3′,5′-di-t-butylphenyl]indenyl;2-iso-butyl-4-[3′,5′-di-t-butylphenyl]indenyl;2-n-butyl-4-[3′,5′-di-t-butylphenyl]indenyl;2-sec-butyl-4-[3′,5′-di-t-butylphenyl] indenyl;2-methyl-4-[3′,5′-di-phenylphenyl]indenyl;2-ethyl-4-[3′,5′-di-phenylphenyl] indenyl;2-n-propyl-4-[3′,5′-di-phenylphenyl]indenyl;2-iso-propyl-4-[3′,5′-di-phenylphenyl]indenyl;2-n-butyl-4-[3′,5′-di-phenylphenyl]indenyl;2-sec-butyl-4-[3′,5′-di-phenylphenyl]indenyl;2-tert-butyl-4-[3′,5′-di-phenylphenyl]indenyl; and the like. Furtherillustrative, but not limiting examples of preferred stereospecificmetallocene compounds are the racemic isomers of9-silafluorenylbis(indenyl) metal dichloride, -diethyl or -dimethyl,wherein the metal is titanium, zirconium or hafnium. Again,unsubstituted indenyl radicals are particularly preferred. In someembodiments, however the two indenyl groups may be replaced,independently of each other, by any of the substituted indenyl radicalslisted above.

Particularly preferred metallocenes as transition metal compounds foruse in the catalyst systems of the present invention together with theactivators of formula (1) or (2) defined above for use in polymerizingolefins are rac-dimethylsilylbis(indenyl) hafnocenes or -zirconocenes,rac-dimethylsilylbis(2-methyl-4-phenylindenyl) hafnocenes or-zirconocenes, rac-dimethylsilylbis(2-methyl-indenyl) hafnocenes or-zirconocenes, and rac-dimethylsilylbis(2-methyl-4-naphthylindenyl)hafnocenes or -zirconocenes, wherein the hafnium and zirconium metal issubstituted, in addition to the bridged bis(indenyl) substituent, by twofurther substituents, which are halogen, preferably chlorine or bromineatoms, or alkyl groups, preferably methyl and/or ethyl groups.Preferably, these additional substituents are both chlorine atoms orboth methyl groups. Particularly preferred transition metal compoundsare dimethylsilylbis(indenyl)hafnium dimethyl,rac-dimethylsilylbis(indenyl)zirconium dimethyl,rac-ethylenylbis(indenyl)zirconium dimethyl, andrac-ethylenylbis(indenyl)hafnium dimethyl.

Illustrative, but not limiting examples of preferred non-stereospecificmetallocene catalysts are:[dimethylsilanediyl(tetramethylcyclopentadienyl)-(cyclododecylamido)]metaldihalide,[dimethylsilanediyl(tetramethylcyclopentadienyl)(t-butylamido)]metaldihalide,[dimethylsilanediyl(tetramethylcyclopentadienyl)(exo-2-norbornyl)]metaldihalide, wherein the metal is Zr, Hf, or Ti, preferably Ti, and thehalide is preferably chlorine or bromine.

In a preferred embodiment, the transition metal compound is a bridged orunbridged bis(substituted or unsubstituted indenyl) hafnium dialkyl ordihalide.

Finally, also non-metallocene compounds that are active in catalyzingolefin polymerization reactions are suitable as the transition metalcompound in the catalyst systems and the processes of the presentinvention. A particularly preferred species of non-metallocene catalystsare the pyridyl amines disclosed e.g., in WO 03/040201.

Activators and Activation Methods for Catalyst Compounds

The transition metal compounds are activated to yield the catalyticallyactive, cationic transition metal compound having a vacant coordinationsite to which a monomer will coordinate and then be inserted into thegrowing polymer chain. In the process for polymerizing olefins accordingto the present invention, an activator of the following general formulae(1) or (2) is used to activate the transition metal compound:

Formula (1) is: [R¹R²R³AH]⁺[Y]⁻  (1)

wherein [Y]⁻ is a non-coordinating anion (NCA) as further illustratedbelow,A is nitrogen or phosphorus,R¹ and R² are hydrocarbyl groups or heteroatom-containing hydrocarbylgroups and together form a first, 3- to 10-membered non-aromatic ringwith A, wherein any number of adjacent ring members may optionally bemembers of at least one second, aromatic or aliphatic ring or aliphaticand/or aromatic ring system of two or more rings, wherein said at leastone second ring or ring system is fused to said first ring, and whereinany atom of the first and/or at least one second ring or ring system isa carbon atom or a heteroatom and may be substituted independently byone or more substituents selected from the group consisting of ahydrogen atom, halogen atom, C₁ to C₁₀ alkyl, C₅ to C₁₅ aryl, C₆ to C₂₅arylalkyl, and C₆ to C₂₅ alkylaryl, andR³ is a hydrogen atom or C₁ to C₁₀ alkyl, or R³ is a C₁ to C₁₀ alkylenegroup that connects to said first ring and/or to said at least onesecond ring or ring system.

Formula (2) is: [R_(n)AH]⁺[Y]⁻  (2)

wherein [Y]⁻ is a non-coordinating anion (NCA) as further illustratedbelow,A is nitrogen, phosphorus or oxygen,n is 3 if A is nitrogen or phosphorus, and n is 2 if A is oxygen,and the groups R are identical or different and are a C₁ to C₃ alkylgroup.

The present invention thus specifically relates to the new catalystsystem itself, comprising a transition metal compound and an activatorof the formula (1) shown above, to the use of an activator of saidformula (1) for activating a transition metal compound in a catalystsystem for polymerizing olefins, and to a process for polymerizingolefins the process comprising contacting under polymerizationconditions one or more olefins with a catalyst system comprising atransition metal compound and an activator of formula (1).

The present invention also relates to a process for polymerizingolefins, the process comprising contacting, under polymerizationconditions, one or more olefins with a catalyst system comprising atransition metal compound and an activator of formula (2) as shownabove. In this process, the Mw of the polymer formed increases withincreasing monomer conversion at a given reaction temperature.

Both the cation part of formulae (1) and (2) as well as the anion partthereof, which is an NCA, will be further illustrated below. Anycombinations of cations and NCAs disclosed herein are suitable to beused in the processes of the present invention and are thus incorporatedherein.

Activators—The Cations

The cation component of the activator of formulae (1) or (2) above isusually a protonated Lewis base capable of protonating a moiety, such asan alkyl or aryl, from the transition metal compound. Thus, upon releaseof a neutral leaving group (e.g. an alkane resulting from thecombination of a proton donated from the cationic component of theactivator and an alkyl substituent of the transition metal compound) atransition metal cation results, which is the catalytically activespecies.

In the polymerization process of the present invention an activator ofabove-depicted formula (2) may be used, wherein the cationic componenthas the formula [R_(n)AH]⁺, wherein:

A is nitrogen, phosphorus or oxygen,n is 3 if A is nitrogen or phosphorus, and n is 2 if A is oxygen,and the groups R are identical or different and are a C₁ to C₃ alkylgroup. [R_(n)AH]⁺ may thus be an ammonium, phosphonium or oxoniumcomponent, as A may be nitrogen, phosphorus or oxygen.

In one preferred embodiment of formula [R_(n)AH]⁺, A is nitrogen orphosphorus, and thus n is 3, and the groups R are identical. Morepreferably, n is 3, and the groups R are all identically methyl, ethylor propyl groups, more preferably [R_(n)AH]⁺ is trimethylammonium or-phosphonium, triethylammonium or -phosphonium, tri(iso-propyl)ammoniumor -phosphonium, tri(n-propyl)ammonium or -phosphonium.Trimethylammonium is particularly preferred. If [R_(n)AH]⁺ is an oxoniumcompound (with n being 2), it is preferably the oxonium derivative ofdimethyl ether, diethyl ether, tetrahydrofurane and dioxane.

In another embodiment, an activator of above-depicted formula (1) isused in the polymerization process of the present invention, thecationic component of which has the formula [R¹R²R³AH]⁺, wherein A isnitrogen or phosphorus, R¹ and R² are hydrocarbyl groups orheteroatom-containing hydrocarbyl groups and together form a first, 3-to 10-membered non-aromatic ring with A, wherein any number, preferablytwo, three, four or five, more preferably two, of adjacent ring membersmay optionally be members of at least one second, aromatic or aliphaticring or aliphatic and/or aromatic ring system of two or more rings,wherein said at least one second ring or ring system is fused to saidfirst ring, and wherein any atom of the first and/or at least one secondring or ring system is a carbon atom or a heteroatom and mayindependently be substituted by one or more substituents selected fromthe group consisting of a hydrogen atom, halogen atom, C₁ to C₁₀ alkyl,preferably C₁ to C₅ alkyl, C₅ to C₁₅ aryl, preferably C₅ to C₁₀ aryl, C₆to C₂₅ arylalkyl, and C₆ to C₂₅ alkylaryl, and R³ is a hydrogen atom orC₁ to C₁₀ alkyl or a C₁ to C₁₀ alkylene group that connects to saidfirst ring and/or said at least second ring or ring system. Since R¹ andR² may also be heteroatom (e.g. nitrogen, phosphorus oroxygen)-containing hydrocarbyl groups, the 3- to 10-membered ring theyare forming with A and/or the at least one second ring or ring systemmay contain one or more additional heteroatoms (in addition to A), suchas nitrogen and/or oxygen. Nitrogen is a preferred additional heteroatomthat may be contained once or several times in said first ring and/orsaid at least one second ring or ring system. Any additional heteroatom,preferably nitrogen, may preferably be substituted independently by ahydrogen atom, or C₁ to C₅ alkyl.

One preferred embodiment of the cation in formula (1) is depicted in thefollowing formula (1)′:

In formula (1)′ R¹ and R² together are a —(CH₂)_(a)— (i.e., alkylene)group with a being 3, 4, 5 or 6, and A is preferably nitrogen, R³ is ahydrogen atom or C₁ to C₁₀ alkyl, or R³ is a C₁ to C₁₀ alkylene groupthat connects to the ring formed by A, R¹, and R². In a specificembodiment, R³ is an alkylene group with 1, 2 or 3 carbon atoms which isconnected to the ring formed by R¹, R² and A. R¹, R² and/or R³ may alsobe aza- or oxa-alkylene groups. R¹ and R² preferably form a 4-, 5-, 6-or 7-membered, non-aromatic ring with the nitrogen atom A.

Preferably, A in formula (1) or (1)′ is nitrogen, and R¹ and R² togetherare a —(CH₂)_(a)— group (also referred to as “alkylene” group) with abeing 3, 4, 5 or 6, or R¹ and R² may also be aza- or oxa-alkylene groupsas mentioned above. R¹ and R² preferably form a 4, 5-, 6- or 7-membered,non-aromatic ring with the nitrogen atom A. Non-limiting examples ofsuch ring are piperidinium, pyrrolidinium, piperazinium, indolinium,isoindolinium, imidazolidinium, morpholinium, pyrazolinium etc. Theadditional substituent at A, R³, is in any of these cases preferably C₁to C₅ alkyl, more preferably C₁ to C₄ alkyl, even more preferably C₁ toC₃ alkyl, and more preferably methyl or ethyl. R₃ may also be a C₁ to C₅alkylene group, preferably a C₁ to C₄ alkylene group, more preferably aC₁ to C₃ alkylene group and more preferably a —(CH₂)₃—, —(CH₂)₂ or —CH₂—group that connects to the first ring containing R¹, R² and A and/or theat least second ring or ring system fused to the first ring. Thus,[R¹R²R³AH]⁺ can also form a tricyclic structure, for example but notlimited to the following ones (which may be further substituted in oneor more positions by any substituents mentioned above and may containunsaturations, but are preferably not aromatic):

If additional heteroatoms are present in the first ring and/or the atleast one second ring or ring system, structures like the following,nonlimiting example (which, again, may be further substituted by one ormore substituents as mentioned above and may contain unsaturations, butare preferably not aromatic) may be used as the cation:

In another preferred embodiment the ring formed by R¹, R² and A is fusedto at least one other aliphatic or aromatic ring or ring system. Forexample, in the case that R¹, R² and A form a 5- or 6-membered aliphaticfirst ring with the heteroatom being phosphorus or nitrogen, one or more5- or 6-membered aromatic rings or ring systems may be fused to saidfirst ring via adjacent carbon atoms of the first ring.

In a preferred embodiment, [R¹R²R³AH]⁺ is N-methylpyrrolidinium,N-methylpiperidinium, N-methyldihydroindolinium orN-methyldihydroisoindolinium.

In another preferred embodiment the cation in formula (1) is depicted asone of the following four formulae (which are based upon formula (1) andare included when formula (1) is referred to herein):

wherein each x is 0, 1 or 2, y is 3, 4, 5, 6, 7, 8, 9, or 10,(preferably 3, 4, 5, or 6), v is 1, 2, 3, 4, 5, 6, or 7 (preferably 0,1, 2 or 3), z is 1, 2, 3, 4, 5, 6, or 7 (preferably 0, 1, 2 or 3), andv+y+z=3, 4, 5, 6, 7, 8, 9, or 10 (preferably v+y+z=3, 4, 5 or 6), m is1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 (preferably 1, 2, 3, or 4), A isnitrogen or phosphorus (preferably nitrogen), R³ is a hydrogen atom orC₁ to C₁₀ alkyl, R* is a C₁ to C₁₀ alkyl, where any of the (CH_(x))groups may be substituted, independently, by one or more substituentsselected from the group consisting of a halogen atom, C₁ to C₁₀ alkyl,C₅ to C₁₅ aryl, C₆ to C₂₅ arylalkyl, and C₆ to C₂₅ alkylaryl. In anotherembodiment, at least one of the (CH_(x)) groups is replaced by aheteroatom, preferably nitrogen. In a preferred embodiment, the ringsdepicted in the formulae above are saturated or partially unsaturated,but are preferably not aromatic. Alternately, the ring containing(CH_(x))_(v), (CH_(x))_(y), and (CH_(x))_(z) is not aromatic, while thering containing (CH_(x))_(m) may or may not be aromatic.

The activator in the present process may also be a combination of atleast two different activators of formulas (1) and/or (2). For exampletwo different ammonium components may be used at the same time with thesame or different NCA's. Using two different cationic compounds in theactivators according to formulas (1) and/or (2) can result in broadenedMWDs and a broader range of melting points in the resulting polyolefinsand can thus be used to tailor polymer properties. For example,N-methylpyrrolidinium and trimethylammonium may be used in combinationtogether with the same NCA as defined below, particularly those such astetrakis(pentafluorophenyl)borate andtetrakis(heptafluoronaphthyl)borate. Furthermore, in order to obtain thesame effect as a mixture of cationic components, an activator with onecationic component may be used, while a second Lewis base may be addedas a free base.

The Non-Coordinating Anion (NCA)

In the activators of formulae (1) and (2) above, [Y]⁻ is anon-coordinating anion (NCA). The term “non-coordinating anion” means ananion that does not coordinate to the metal cation of the catalyst orthat does coordinate to the metal cation, but only weakly. NCA's areusually relatively large (bulky) and capable of stabilizing the activecatalyst species which is formed when the compound and the activator arecombined. Said anion must still be sufficiently labile to be displacedby unsaturated monomers. Further, the anion will not transfer an anionicsubstituent or fragment to the cation of the transition metal compoundas to cause it to form a neutral transition metal compound and a neutralby-product from the anion. Thus, suitable NCAs are those which are notdegraded to neutrality when the initially formed complex decomposes. Twoclasses of compatible NCAs useful herein have been disclosed e.g. inEP-A-0 277 003 and EP-A-0277 004. They include: 1) anionic coordinationcomplexes comprising a plurality of lipophilic radicals covalentlycoordinated to and shielding a central charge-bearing metal or metalloidcore, and 2) anions comprising a plurality of boron atoms such ascarboranes, metallacarboranes and boranes.

The anion component [Y]⁻ includes those having the formula[M^(k+)Q_(n)]^(d−) wherein k is an integer from 1 to 3; n is an integerfrom 2 to 6; n−k=d; M is an element selected from group 13 of thePeriodic Table of the Elements, preferably boron or aluminum, and Q isindependently a hydride, bridged or unbridged dialkylamido, halide,alkoxide, aryloxide, hydrocarbyl, substituted hydrocarbyl, halocarbyl,substituted halocarbyl, and halosubstituted-hydrocarbyl radical, said Qhaving up to 20 carbon atoms with the proviso that in not more than oneoccurrence is Q a halide (but more than one q may be a halide containinggroup). Preferably, each Q is a fluorinated hydrocarbyl having 1 to 20carbon atoms, more preferably each Q is a fluorinated aryl group, andmore preferably each Q is a perfluorinated aryl group. Examples ofsuitable [Y]⁻ also include diboron compounds as those disclosed in U.S.Pat. No. 5,447,895.

[Y]⁻ is preferably [B(R⁴)₄]⁻, with R⁴ being an aryl group or asubstituted aryl group, of which the one or more substituents areidentical or different and are selected from the group consisting ofalkyl, aryl, a halogen atom, halogenated aryl, and haloalkylaryl groups.Preferred examples of [Y]⁻ for use in the present invention are:tetraphenylborate, tetrakis(pentafluorophenyl)borate,tetrakis-(2,3,4,6-tetrafluorophenyl)borate,tetrakis-(perfluoronaphthyl)borate (also referred to astetrakis(heptafluoronaphthyl)borate), tetrakis(perfluorobiphenyl)borate,and tetrakis(3,5-bis(trifluoromethyl)phenyl)borate. Particularlypreferred [Y]⁻ are tetrakis(pentafluorophenyl)borate andtetrakis(heptafluoronaphthyl)borate.

Any of the NCA's [Y]⁻ illustrated herein can be used in combination withany cation component of the activator of formula (1) or (2) as definedhereinabove. Thus, any combination of preferred components [Y]⁻ andpreferred components [R¹R²R³AH]⁺ or [R_(n)AH]⁺ are considered to bedisclosed and suitable in the processes of the present invention.

Preferred Activators

Preferred activators of formula (1) in the catalyst systems of thepresent invention and used in the polymerization processes of thepresent invention are those wherein A is nitrogen, R¹ and R² togetherare a —(CH₂)_(a)— group with a being 3, 4, 5, or 6, and R³ is C₁, C₂,C₃, C₄ or C₅ alkyl, and [Y]⁻ is [B(R⁴)₄]⁻, with R⁴ being an aryl groupor a substituted aryl group, of which the one or more substituents areidentical or different and are selected from the group consisting ofalkyl, aryl, a halogen atom, halogenated aryl, and haloalkylaryl groups,and preferably R⁴ is a perhalogenated aryl group, more preferably aperfluorinated aryl group, more preferably pentafluorophenyl,heptafluoronaphthyl or perfluorobiphenyl. Preferably, these activatorsare combined with transition metal compound (such as a metallocene) toform the catalyst systems of the present invention.

Preferred activators in the catalyst systems of formula (2) in thecatalyst systems used in the polymerization processes of the presentinvention are those wherein A is nitrogen, n is 3, all groups R areidentical and are methyl, ethyl or isopropyl, and [Y]⁻ is [B(R⁴)₄]⁻,with R⁴ being an aryl group or a substituted aryl group, of which theone or more substituents are identical or different and are selectedfrom the group consisting of alkyl, aryl, a halogen atom, halogenatedaryl, and haloalkylaryl groups, and preferably R⁴ is a perhalogenatedaryl group, more preferably a perfluorinated aryl group, more preferablypentafluorophenyl, heptafluoronaphthyl or perfluorobiphenyl. Preferably,these activators are combined with a transition metal compound (such asa metallocene) to form the catalyst systems of the present invention.

In the polymerization process of the present invention, in addition tothe preferred activators of formula (1) mentioned in the precedingparagraph also the activators of formula (2) wherein A is nitrogen andall groups R are identically methyl or ethyl, and wherein [Y]⁻ isdefined as in the preceding paragraph are preferably used. Again, theseactivators are preferably combined with a metallocene (e.g. as explainedherein below) to form the catalyst systems used in the polymerizationprocess of the present invention.

Preferred Catalyst Systems

Preferred combinations of transition metal compound and activator in thecatalyst systems for olefin polymerization according to the presentinvention comprise the following components:

-   -   a metallocene compound, preferably a dialkylsilyl-bridged        bis(indenyl) metallocene, wherein the metal is a group 4 metal        and the indenyl is unsubstituted, or if substituted, is        substituted by one or more substituents selected from the group        consisting of a C₁ to C₁₀ alkyl, C₅ to C₁₅ aryl, C₆ to C₂₅        arylalkyl, and C₆ to C₂₅ alkylaryl; more preferably        dimethylsilylbis(indenyl) metal dichloride or -dimethyl,        ethylenylbis(indenyl) metal dichloride or -dimethyl,        dimethylsilylbis(2-methyl-4-phenylindenyl) metal dichloride or        -dimethyl, dimethylsilylbis(2-methyl-indenyl) metal dichloride        or -dimethyl, and dimethylsilylbis(2-methyl-4-naphthylindenyl)        metal dichloride or -dimethyl, wherein in all cases the metal        may be zirconium or hafnium;    -   a cationic component [R¹R²R³AH]⁺ wherein preferably A is        nitrogen, R¹ and R² are together an —(CH₂)_(a)— group, wherein a        is 3, 4, 5 or 6 and form, together with the nitrogen atom, a 4-,        5-, 6- or 7-membered non-aromatic ring to which, via adjacent        ring carbon atoms, optionally one or more aromatic or        heteroaromatic rings may be fused, and R³ is C₁, C₂, C₃, C₄ or        C₅ alkyl, more preferably N-methylpyrrolidinium or        N-methylpiperidinium; or a cationic component [R_(n)AH]⁺ wherein        preferably A is nitrogen, n is 3 and all R are identical and are        C₁ to C₃ alkyl groups, more preferably trimethylammonium or        triethylammonium; and    -   an anionic component [Y]⁻ which is an NCA, preferably of the        formula [B(R⁴)₄]⁻, with R⁴ being an aryl group or a substituted        aryl group, of which the one or more substituents are identical        or different and are selected from the group consisting of        alkyl, aryl, a halogen atom, halogenated aryl, and haloalkylaryl        groups, preferably perhalogenated aryl groups, more preferably        perfluorinated aryl groups, and more preferably        pentafluorophenyl, heptafluoronaphthyl or perfluorobiphenyl.

More preferably, the activator for use in any of the polymerizationprocesses according to the present invention is trimethylammoniumtetrakis(pentafluorophenyl)borate, N-methylpyrrolidiniumtetrakis(pentafluorophenyl)borate, trimethylammoniumtetrakis(heptafluoronaphthyl)borate, or N-methylpyrrolidiniumtetrakis(heptafluoronaphthyl) borate. The metallocene is preferablyrac-dimethylsilyl bis(indenyl)zirconium dichloride or -dimethyl,rac-dimethylsilyl bis(indenyl)hafnium dichloride or -dimethyl,rac-ethylenyl bis(indenyl)zirconium dichloride or -dimethyl orrac-ethylenyl bis(indenyl)hafnium dichloride or -dimethyl.

In another embodiment, a preferred transition metal compound comprises abis indenyl compound represented by the formula:

wherein M is a group 4 metal, preferably hafnium, T is a bridging group(such as an alkylene (methylene, ethylene) or a di substituted silyl orgermyl group, (such as dimethyl silyl)), n is 0 or 1, R₂, R₃, R₄, R₅,R₆, and R₇ are hydrogen, a heteroatom, a substituted heteroatom group, asubstituted or unsubstituted alkyl group, and a substituted orunsubstituted aryl group (preferably a substituted or unsubstitutedalkyl or a substituted or unsubstituted aryl group). In a preferredembodiment R₂ is hydrogen. In another preferred embodiment R₂ and R₄ arehydrogen. In another preferred embodiment R₂ is hydrogen and R₄ is C₁ toC₂₀ alkyl (preferably methyl) or an aryl group (such as substituted orunsubstituted phenyl). In another preferred embodiment R₂ and R₄ aremethyl. In another embodiment R₂ and R₄ are not methyl. In anotherembodiment R₂ is not methyl. In another preferred embodiment, R₃, R₄,R₅, R₆, and R₇ are hydrogen and R₂ is substituted or unsubstituted alkylor substituted or unsubstituted aryl (preferably methyl). In anotherpreferred embodiment, R₂, R₃, R₅, R₆, and R₇ are hydrogen and R₄ issubstituted or unsubstituted alkyl or substituted or unsubstituted aryl(preferably methyl or phenyl).

Any catalyst system resulting from any combination of the preferredmetallocene compound, preferred cationic component of the activator andpreferred anionic component of the activator mentioned in the precedingparagraph shall be explicitly disclosed and may be used in accordancewith the present invention in the polymerization of one or more olefinmonomers. Also, combinations of two different activators can be usedwith the same or different metallocene(s).

Scavengers or Additional Activators

The catalyst systems suitable for all aspects of the present inventionmay contain, in addition to the transition metal compound and theactivator described above, also additional (additional activators orscavengers) as explained in the following.

A co-activator is a compound capable of alkylating the transition metalcomplex, such that when used in combination with an activator, an activecatalyst is formed. Co-activators include alumoxanes as mentioned in thefollowing, and aluminum alkyls as further listed below. An alumoxane ispreferably an oligomeric aluminum compound represented by the generalformula (R^(x)—Al—O)_(n), which is a cyclic compound, or R^(x)(R^(x)—Al—O)_(n)AlR^(x) ₂, which is a linear compound. Most commonalumoxane is a mixture of the cyclic and linear compounds. In thegeneral alumoxane formula, R^(x) is independently a C₁-C₂₀ alkylradical, for example, methyl, ethyl, propyl, butyl, pentyl, isomersthereof, and the like, and “n” is an integer from 1-50. More preferably,R^(x) is methyl and “n” is at least 4. Methyl alumoxane (MAO) as well asmodified MAO, referred to herein as MMAO, containing some higher alkylgroups to improve the solubility, ethyl alumoxane, iso-butyl alumoxaneand the like are useful herein. Particularly useful MAO can be purchasedfrom Albemarle in a 10 wt. % solution in toluene. Co-activators aretypically only used in combination with Lewis acid activators and ionicactivators when the pre-catalyst is not a dihydrocarbyl or dihydridecomplex.

In some embodiments of the invention, scavengers may be used to “clean”the reaction of any poisons that would otherwise react with the catalystand deactivate it. Typical aluminum or boron alkyl components useful asscavengers are represented by the general formula R^(x)JZ₂ where J isaluminum or boron, R^(x) is a C₁-C₂₀ alkyl radical, for example, methyl,ethyl, propyl, butyl, pentyl, and isomers thereof, and each Z isindependently R^(x) or a different univalent anionic ligand such ashalogen (Cl, Br, I), alkoxide (OR^(x)) and the like. More preferredaluminum alkyls include triethylaluminum, diethylaluminum chloride,ethylaluminium dichloride, tri-iso-butylaluminum, tri-n-octylaluminum,tri-n-hexylaluminum, trimethylaluminum and combinations thereof.Preferred boron alkyls include triethylboron. Scavenging compounds mayalso be alumoxanes and modified alumoxanes including methylalumoxane andmodified methylalumoxane.

Method of Preparing Catalyst System

The catalyst systems of the present invention can be prepared accordingto methods known in the art. For obtaining the cations of the activatorsof formula (1) or (2) as defined hereinabove, for example ammoniumcations can be provided as salts that can be synthesized by the reactionof an amine with an acid in which the conjugate base of the acid remainsas the counteranion or is exchanged with other anions. See “OrganicChemistry,” Pine et al., 4^(th) edition, McGraw-Hill, 1980. A usefulsynthesis for example is the reaction of a slight excess of HCl (as anEt₂O solution) with the amine in hexanes resulting in the immediateprecipitation of the amine hydrochloride. The chloride can be replacedby anion exchange with a suitable NCA according to the presentinvention. See references Chemische Berichte, 1955, Vol. 88, p. 962, orU.S. Pat. No. 5,153,157 and references therein. Phosphines and ethersare similarly protonated with acids and can undergo anion exchangereactions to the desired phosphonium salts, see for example GermanPatent DE 2116439.

The catalyst systems may also include a support material or carrier.Generally the support is a porous material, for example, talc, or aninorganic oxide. Other suitable support materials include zeolites,clays, and organoclays.

Preferred support materials are inorganic oxides that include Group 2,3, 4, 5, 13 or 14 metal oxides. Preferred supports include silica, whichmay or may not be dehydrated, fumed silica, alumina (WO 99/60033),silica-alumina and mixtures thereof. Other useful supports includemagnesia, titania, zirconia, montmorillonite (European Patent EP-B1 0511 665), phyllosilicate, zeolites, talc, clays (U.S. Pat. No.6,034,187) and the like. Also, combinations of these support materialsmay be used, for example, silica-chromium, silica-alumina,silica-titania and the like.

It is preferred that the support material have a surface area in therange of from about 10 to about 700 m²/g, pore volume in the range offrom about 0.1 to about 4.0 cc/g and average particle size in the rangeof from about 5 to about 500 μm. More preferably, the surface area ofthe support material is in the range of from about 50 to about 500 m²/g,pore volume of from about 0.5 to about 3.5 cc/g and average particlesize of from about 10 to about 200 μm. More preferably, the surface areaof the support material is in the range is from about 100 to about 400m²/g, pore volume from about 0.8 to about 3.0 cc/g and average particlesize is from about 5 to about 100 μm. The average pore size of thecarrier useful in the invention typically has pore size in the range offrom 10 to 1000 Å, preferably 50 to about 500 Å, and more preferably 75to about 350 Å.

Polymerization Process

Any known polymerization process may be used to produce the presentcopolymer. Polymerization methods include high pressure, slurry, gas,bulk, suspension, supercritical, solution phase, and combinationthereof. The catalysts can be in the form of a homogeneous solution,supported, or a combination thereof. Polymerization may be carried outby a continuous, a semi-continuous or batch process and may include useof chain transfer agents, scavengers, or other such additives as deemedapplicable. By continuous process is meant that there is continuousaddition to, and withdrawal of reactants and products from, the reactorsystem. Continuous processes can be operated in steady state, i.e., thecomposition of effluent remains fixed with time if the flow rate,temperature/pressure and feed composition remain invariant. For examplea continuous process to produce a polymer would be one where thereactants are continuously introduced into one or more reactors andpolymer product is continuously withdrawn.

The catalyst systems described herein can be used advantageously in ahomogeneous solution process. Generally this involves polymerization ina continuous reactor in which the polymer formed and the startingmonomer and catalyst materials supplied are agitated to reduce or avoidconcentration gradients. Some useful processes operate above the cloudpoint of the polymers at high pressures. Reaction environments includethe case where the monomer(s) acts as diluent or solvent as well as thecase where a liquid hydrocarbon is used as diluent or solvent. Preferredhydrocarbon liquids include both aliphatic and aromatic fluids such asdesulphurized light virgin naphtha and alkanes, such as propane,isobutene, mixed butanes, hexane, pentane, isopentane, isohexane,cyclohexane, isooctane, and octane.

Temperature control in the reactor is typically obtained by balancingthe heat of polymerization with reactor cooling by reactor jackets orcooling coils to cool the contents of the reactor, auto refrigeration,pre-chilled feeds, vaporization of liquid medium (diluent, monomers orsolvent) or combinations of all three. Adiabatic reactors withpre-chilled feeds may also be used. The reactor temperature also dependson the catalyst used. In general, the reactor temperature is in therange from about 30° C. to about 250° C., preferably from about 60° C.to about 200° C. The pressure is generally in the range from atmosphericpressure up to high pressures such as about 300 MPa, about 200 MPa orabout 100 MPa. Also lower pressures up to about 50, about 40, about 30,about 20 or about 15 MPa are suitable. The lower end of the possiblepressure range may be anything from about 0.1 MPa, such as 0.5 MPa,about 1 MPa or about 2.0 MPa. In at least one specific embodiment, thereactor pressure is less than 600 pounds per square inch (psi) (4.14MPa), or less than 500 psi (3.45 MPa) or less than 400 psi (2.76 MPa),or less than 300 psi (2.1 MPa), such as from about atmospheric pressureto about 400 psi (2.76 MPa). In another embodiment reactor pressure isfrom about 400 psi (2.76 MPa) to about 4000 psi (27.6 MPa), or fromabout 1000 psi (6.9 MPa) to 2000 psi (13.8 MPa), or from about 1200 psi(8.27 MPa) to 1800 psi (12.4 MPa).

The monomer concentration in the reactor (based on the entire reactionmixture) may be anywhere from very dilute up to using a monomer as thesolvent. Suitable monomer concentrations may be, for example up to about2 mol/L, up to about 5 mol/L, up to about 10 mol/L, or even higher, suchas up to about 15 mol/L.

Uses of the Copolymer

The ethylene-based copolymers described herein, both alone and incombination with other materials, are suitable for use in such articlesas films, fibers and nonwoven fabrics, extruded and molded articles.Examples of films include blown or cast films formed by coextrusion orby lamination useful as shrink film, cling film, stretch film, sealingfilms, oriented films, snack packaging, heavy duty bags, grocery sacks,baked and frozen food packaging, medical packaging, industrial liners,membranes, etc. in food-contact and non-food contact applications.Examples of fibers include but are not limited to spun bond and meltblown fiber operations for use in woven or non-woven form to makefilters, diaper fabrics, hygiene products, medical garments,geotextiles, etc. Examples of extruded or molded articles includetubing, medical tubing, or wire and cable coatings.

Other desirable articles that can be made from and/or incorporate thecopolymers include automotive components and sporting equipment. Moreparticularly, automotive components include such as bumpers, grills,trim parts, dashboards and instrument panels, exterior door and hoodcomponents, spoiler, wind screen, hub caps, mirror housing, body panel,protective side molding, and other interior and external componentsassociated with automobiles, trucks, boats, and other vehicles.

Other articles that may be formed by any extrusion or molding techniqueinclude or incorporate liquid storage containers for medical uses suchas bags, pouches, and bottles for storage and IV infusion of blood orsolutions; wrapping or containing food preserved by irradiation, othermedical devices including infusion kits, catheters, and respiratorytherapy, as well as packaging materials for medical devices and foodwhich may be irradiated by gamma or ultraviolet radiation includingtrays, as well as stored liquid, particularly water, milk, or juice,containers including unit servings and bulk storage containers.

The ethylene-based copolymers described herein, particularly at lowethylene contents, are also useful as rheology modifiers and, inparticular, viscosity enhancers, for lubricating oil compositions.Examples of the lubricating base oils that can be used with the currentcopolymers include mineral oils and synthetic oils, such aspoly-α-olefins, polyol esters, and polyalkylene glycols. A mineral oilor a blend of a mineral oil and a synthetic oil is preferably employed.The mineral oil is generally used after purification such as dewaxing.Although mineral oils are divided into several classes according to thepurification method, suitable mineral oils generally have a wax contentof about 0.5 wt. % to about 10 wt. %. Further, a mineral oil having akinematic viscosity of 10 to 200 cSt is generally used.

Suitable base oils include those conventionally employed as crankcaselubricating oils for spark-ignited and compression-ignited internalcombustion engines, such as automobile and truck engines, marine andrailroad diesel engines, and the like. Advantageous results are alsoachieved by employing the ethylene-based copolymers in base oilsconventionally employed in and/or adapted for use as power transmittingfluids such as automatic transmission fluids, tractor fluids, universaltractor fluids and hydraulic fluids, heavy duty hydraulic fluids, powersteering fluids and the like. Gear lubricants, industrial oils, pumpoils and other lubricating oil compositions can also benefit from theincorporation of the present ethylene-based copolymers.

Suitable base oils include not only hydrocarbon oils derived frompetroleum, but also include synthetic lubricating oils such as esters ofdibasic acids, complex esters made by esterification of monobasic acids,polyglycols, dibasic acids and alcohols, polyolefin oils, etc. Thus,ethylene-based copolymers are suitably incorporated into synthetic baseoils such as alkyl esters of dicarboxylic acids, polyglycols andalcohols, polyalpha-olefins, polybutenes, alkyl benzenes, organic estersof phosphoric acids, polysilicone oils.

The above oil compositions may optionally contain other conventionaladditives, such as, for example, pour point depressants, antiwearagents, antioxidants, other viscosity-index improvers, dispersants,corrosion inhibitors, anti-foaming agents, detergents, rust inhibitors,friction modifiers, and the like.

In general, the amount of the present ethylene-based copolymer added toa lubricating oil composition to increase its viscosity is between about0.01 wt. % and about 10 wt. %, such as between about 0.2 wt. % and about5 wt % of said lubricating oil composition.

The ethylene-based copolymers are also useful as blending components forconventional polymer compositions, e.g., ethylene homopolymers orcopolymers, or propylene homopolymers or copolymers, and inthermoplastic vulcanizates (“TPV”). Further, such ethylene-basedcopolymers can be useful as additives or primary components in moldedarticles, extrudates, films, e.g., blown films, etc., woven and nonwovenfabrics, adhesives, and conventional elastomer applications.

Particularly when produced by solution polymerization, the presentcopolymers will provide free-flowing pellets having a melt flow rate(MFR) in the range of about 0.5 to about 10 g/10 minutes (as measured at230° C. and 2.16 kg). It will be appreciated that such pellets will haveless tendency to cohere together and agglomerate and to the processingequipment en route to the duster, in the duster itself, and in theconveying equipment from the duster to the baler as compared withpolymers that have no crystallinity or have a melting point below theoperating temperature of the finishing equipment (about 30° C.). Inaddition, conventional polymers, that have an MFR above 2 g/10 minutesthat are amorphous or have a melting point below the operatingtemperature of the finishing equipment (about 30° C.), have nostructural integrity and are typically packaged in bales. The presentcopolymers can be packaged in bags, which is more efficient andeconomical.

The invention will now be more particularly described with reference tothe Examples and the accompanying drawing.

In the Examples weight-average and number-average molecular weights weredetermined by GPC using a Waters Alliance 2000 gel permeationchromatograph equipped with a Waters differential refractometer thatmeasures the difference between the refractive index of the solvent andthat of the solvent containing the fractionated polymer. The system wasused at 145° C. with 1,2,4-Trichlorobenzene (TCB) as the mobile phasethat was stabilized with ˜250 ppm of butylated hydroxy toluene (BHT).The flow rate used was 1.0 mL/min. Three (Polymer Laboratories) PLgelMixed-B columns were used. This technique is discussed in“Macromolecules,” Vol. 34, No. 19, pp. 6812-6820, and “Macromolecules,”Vol. 37, No. 11, pp. 4304-4312, both of which are incorporated herein byreference.

The separation efficiency of the column set was calibrated using aseries of narrow molecular weight distribution polystyrene standards,which reflects the expected molecular weight range for samples and theexclusion limits of the column set. At least 10 individual polystyrenestandards, ranging from Mp ˜580 to 10,000,000, were used to generate thecalibration curve. The polystyrene standards were obtained from PolymerLaboratories (Amherst, Mass.) or an equivalent source. To assureinternal consistency, the flow rate was corrected for each calibrant runto give a common peak position for the flow rate marker (taken to be thepositive inject peak) before determining the retention volume for eachpolystyrene standard. The flow marker peak position thus assigned wasalso used to correct the flow rate when analyzing samples; therefore, itis an essential part of the calibration procedure. A calibration curve(log Mp vs. retention volume) was generated by recording the retentionvolume at the peak in the DRI signal for each PS standard, and fittingthis data set to a second order polynomial. Polystyrene standards weregraphed using Viscotec 3.0 software. Samples were analyzed usingWaveMetrics, Inc. IGOR Pro and Viscotec 3.0 software using updatedcalibration constants.

Peak melting point (Tm) and peak crystallization temperature (Tc), glasstransition temperature (Tg), and heat of fusion (ΔH) were determinedusing the following procedure according to ASTM D3418-03. Differentialscanning calorimetric (DSC) data were obtained using a Perkin ElmerPyris 1 machine. Samples weighing approximately 5-10 mg were sealed inan aluminum hermetic sample pan. The DSC data were recorded by firstgradually heating the sample to 200° C. at a rate of 10° C./minute. Thesample was kept at 200° C. for 5 minutes then cooled down to −100° C. ata rate of 10° C./minute before a second cooling-heating cycle wasapplied. Both the first and second cycle thermal events were recorded.Areas under the endothermic peaks of the 2^(nd) melting curve weremeasured and used to determine the heat of fusion. The melting andcrystallization temperatures reported here were obtained during thesecond heating/cooling cycle.

The ethylene content of ethylene/propylene copolymers was determinedusing FTIR according to the following technique. A thin homogeneous filmof polymer, pressed at a temperature of about 150° C., was mounted on aPerkin Elmer Spectrum 2000 infrared spectrophotometer. A full spectrumof the sample from 600 cm⁻¹ to 4000 cm⁻¹ was recorded and the area underthe propylene band at ˜1165 cm⁻¹ and the area under the ethylene band at˜732 cm⁻¹ in the spectrum were calculated. The baseline integrationrange for the methylene rocking band is nominally from 695 cm⁻¹ to theminimum between 745 and 775 cm⁻¹. For the polypropylene band thebaseline and integration range is nominally from 1195 to 1126 cm⁻¹. Theethylene content in wt. % was calculated according to the followingequation:

ethylene content (wt. %)=72.698−86.495X+13.696X ²

where X=AR/(AR+1) and AR is the ratio of the area for the peak at ˜1165cm⁻¹ to the area of the peak at ˜732 cm⁻¹.

Additional Specific Embodiments

Also provided are the following additional embodiments:

A. An ethylene copolymer comprising 40 wt. % to 70 wt. % of unitsderived from ethylene and at least 30 wt. % of units derived from atleast one α-olefin having 3 to 20 carbon atoms, wherein the copolymerhas the following properties:

(a) a weight-average molecular weight (Mw), as measured by GPC, in therange of 50,000 to 200,000 g/mol;

(b) a melting point (Tm) in ° C., as measured by DSC, that satisfies therelation:

Tm>3.4×E−180

where E is the weight % of units derived from ethylene in the copolymer;

(c) a ratio of Mw/Mn of 1.8 to 2.5;

(d) a content of Group 4 metals of no more than 5 ppm; and

(e) a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of at least3.

B. The copolymer of embodiment A comprising 40 wt. % to 55 wt. % ofunits derived from ethylene.

C. The copolymer of embodiment B comprising 60 wt. % to 45 wt. % ofunits derived from at least one α-olefin having 3 to 20 carbon atoms.

D. The copolymer of any preceding embodiment having a melting point (Tm)in ° C., as measured by DSC, that satisfies the relation:

Tm>3.4×E−170,

preferably Tm>3.4×E−160;

more preferably Tm>3.4×E−90

where E is the weight % of units derived from ethylene in the copolymer.

E. An ethylene copolymer comprising 70 wt. % to 85 wt. % of unitsderived from ethylene and at least 12 wt. % of units derived from atleast one α-olefin having 3 to 20 carbon atoms, wherein the copolymerhas the following properties:

(a) a weight-average molecular weight (Mw), as measured by GPC, in therange of 50,000 to 200,000 g/mol;

(b) a melting point (Tm), as measured by DSC, of at least 100° C.;

(c) a ratio of Mw/Mn of 1.8 to 2.5;

(d) a content of Group 4 metals of no more than 5 ppm; and

(e) a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of at least3.

F. The copolymer of embodiment E having a melting point (Tm), asmeasured by DSC, of at least 110° C.

G. The copolymer of any preceding embodiment wherein said at least oneα-olefin is selected from propylene, butene, hexene and octene, andpreferably comprises propylene.

H. The copolymer of any preceding embodiment containing no more than 25ppm of Zn.

I. A process of producing the copolymer of any one of embodiments A toD, G and H, the process comprising contacting a monomer mixturecomprising 40 wt. % to 70 wt. % of ethylene and at least 30 wt. % of atleast one α-olefin having 3 to 20 carbon atoms under polymerizationsconditions with a catalyst composition comprising a bridged bis-indenylcomplex of a transition metal.

J. A process of producing the copolymer of any one of embodiments E toH, the process comprising contacting a monomer mixture comprising 70 to85 wt. % of ethylene and at least 12 wt. % of at least one α-olefinhaving 3 to 20 carbon atoms under polymerizations conditions with acatalyst composition comprising a bridged bis-indenyl complex of atransition metal.

K. The process of embodiment I or embodiment J wherein the transitionmetal comprises hafnium and/or zirconium.

L. The process of any one of embodiments I to K wherein the bridgedbis-indenyl complex comprises a dialkylsilyl bridging group, andpreferably comprises dimethylsilylbisindenylhafnium dimethyl.

M. The process of any one of embodiments I to L wherein the catalystcomposition comprises a fluoroarylborate activator, and preferablycomprises a perfluorophenylborate activator.

N. The process of any one of embodiments I to M wherein the catalystcomposition comprises a rac-dimethylsilylbisindenyl hafnium dimethyl anda trimethylammonium tetrakis-pentafluorophenylborate activator.

O. A lubricating oil composition comprising (a) a lubricating oil baseand (b) the ethylene copolymer of any one of embodiments A to D.

Examples 1 to 3

The polymer compositions in Examples 1 and 2 were synthesized in onecontinuous stirred tank reactor. The polymerization was performed insolution, using isohexane as a solvent. In the reactor, polymerizationwas performed at an overall pressure of 290 psi (2 MPa). Ethylene andpropylene feed rates, and reactor temperatures are listed in Table 1.

The catalyst was rac-dimethylsilylbis(indenyl) hafnium dimethyl(metallocene) pre-activated with a trimethylammoniumtetrakis(pentafluorophenyl)borate (activator) in a toluene solution thatwas fed into the reactor. The molar ratio of metallocene to activatorwas about 1:1.03. The metallocene concentration in toluene was 1.74*10⁻⁴moles/liter and the activator concentration was 1.68*10⁻⁴ moles/liter.The feed rate of the catalyst solution is listed in Table 1. Tri n-octylaluminum (TNOA) was dissolved in isohexane at 25 wt % and fed into thereactor as a scavenger. The feed rate of the scavenger solution islisted in Table 1.

In the process, temperature control was used to achieve the desiredmolecular weight. The copolymer solution emerging from the reactor wasstopped from further polymerization by addition of water and thendevolatilized using conventionally known devolatilization methods suchas flashing or liquid phase separation, first by removing the bulk ofthe isohexane to provide a concentrated solution, and then by strippingthe remainder of the solvent in anhydrous conditions using adevolatilizer or a twin screw devolatilizing extruder so as to end upwith a molten polymer composition containing less than 0.5 wt. % ofsolvent and other volatiles. The molten polymer was cooled until solid.

TABLE 1 Example 1 2 3 weight of final polymer 297.2 398 387 (grams) %ethylene in the 46.27 47.09 48.77 product Cat feed rate (g/h) 0.005160.00516 0.00516 TNOA feed rate 3.35 * 10⁻⁴ 3.35 * 10⁻⁴ 3.35 * 10⁻⁴(mol//h) C2 feed rate (g/h) 330 358.7 358.7 C3 feed rate (g/h) 761.4762.17 764.32 C6 feed Rate (g/h) 3564 3564 3564 Reaction temp. (° C.) 6570 80 Production Rate (g/h) 324.6 426.6 402.7

The properties of the resultant copolymers are summarized in Table 2 andin FIG. 1, which also show the properties of copolymers producedaccording to Examples 6 to 8 of U.S. Pat. No. 6,589,920 (‘920 patent’).

TABLE 2 Ethylene DSC melting MFR (g/10 min) (wt %) point (° C.) Example1 0.94 46.27 33.36 Example 2 1.15 47.09 37.87 Example 3 1.4 48.77 43.21‘920 Patent Ex. 6 47.2 −38.5 ‘920 Patent Ex. 7 46.8 −36.2 ‘920 PatentEx. 8 49.6 −40.8

It will be seen that the copolymers of the present Examples 1 to 3 havesubstantially higher, about 60° C. higher, melting points than thepolymers made according to the '920 patent, indicating that the presentpolymers are structurally different than the polymers of the '920patent.

Examples 4 to 6

The polymerization procedure used in Examples 4 to 6 was the same asdescribed in Example 1 except for the reaction parameters summarized inTable 3.

TABLE 3 Example 4 5 6 weight of final polymer 39.5 27.3 103 (grams) %ethylene in the product 57.89 57.75 53.21 Cat feed rate (g/h) 0.005160.00516 0.00516 TNOA feed rate (mol//h) 0.12 0.12 0.12 C2 feed rate(g/h) 785.5 765.7 765.7 C3 feed rate (g/h) 250.9 320.9 320.9 C6 feedRate (g/h) 3564 3564 3564 Reaction temp. (° C.) 100 120 100 ProductionRate (g/h) 101.1 81.1 76.7

The properties of the resultant copolymers are summarized in Table 4 andin FIG. 1.

TABLE 4 Example 4 5 6 MFR 3.085 3.04* 6.89 C2 57.89 57.75 53.21 Mn 4506633931 45917 Mw 110543 71202 98766 Mz 221631 138163 181746 Mw(LS) 11860171296 110109 DSC 59.19 58.52 43 Mw/Mn 2.45 2.10 2.15 Mz/Mw 2.00 1.941.84 Tm DSC 59.19 58.52 43 *Second measurement was 14.5 g/10 min

Examples 7 to 11

The polymerization procedure used in Examples 7 to 11 was the same asdescribed in Example 1 except for the reaction parameters summarized inTable 5 below. The properties of the resultant copolymers are summarizedin Table 6 and in FIG. 1.

TABLE 5 Example 7 8 9 10 11 % ethylene in the 77.1 81.9 75.6 80.8 85.4product Cat feed rate (mol/min) 1.12 * 10⁻⁷ 1.12 * 10⁻⁷ 1.12 * 10⁻⁷1.12 * 10⁻⁷ 1.12 * 10⁻⁷ TNOA feed rate (g/h) C2 feed rate (g/h) 6 8 6 810 C3 feed rate (g/h) 5.09 5.09 5.09 5.09 5.09 C6 feed rate (ml/min) 8080 80 80 80 Reaction temp. (° C.) 130 130 120 120 120 Production rate(g/min) 4.4 5.4 4.7 6.4 7

TABLE 6 Example wt % C2 Tm Mn Mw Mz Mw/Mn Mz/Mw 7 77.1 114.4 8617 52572113630 6.10 2.16 8 81.9 117.83 14223 58027 127331 4.08 2.19 9 75.6115.57 21517 75976 150445 3.53 1.98 10 80.4 117.05 20775 61843 1230782.976799 1.990169 11 85.4 119.46 25840 98553 224636 3.813971 2.279342

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to variations notnecessarily illustrated herein. For this reason, reference should bemade solely to the appended claims for purposes of determining the scopeof the present invention.

1. An ethylene copolymer comprising 40 wt. % to 70 wt. % of unitsderived from ethylene and at least 30 wt. % of units derived from atleast one α-olefin having 3 to 20 carbon atoms, wherein the copolymerhas the following properties: (a) a weight-average molecular weight(Mw), as measured by GPC, in the range of about 50,000 to about 200,000g/mol; (b) a melting point (Tm) in ° C., as measured by DSC, thatsatisfies the relation:Tm>3.4×E−180 where E is the weight % of units derived from ethylene inthe copolymer; (c) a ratio of Mw/Mn of about 1.5 to about 3.5; (d) acontent of Group 4 metals of no more than 25 ppm; and (e) a ratio of wtppm Group 4 metals/wt ppm Group 5 metals of at least
 3. 2. The copolymerof claim 1 comprising 40 wt. % to 55 wt. % of units derived fromethylene.
 3. The copolymer of claim 2 comprising 60 wt. % to 45 wt. % ofunits derived from at least one α-olefin having 3 to 20 carbon atoms. 4.The copolymer of claim 1 wherein said at least one α-olefin is selectedfrom propylene, butene, hexene and octene.
 5. The copolymer of claim 1wherein said at least one α-olefin comprises propylene.
 6. The copolymerof claim 1 having a melting point (Tm) in ° C., as measured by DSC, thatsatisfies the relation:Tm>3.4×E−170 where E is the weight % of units derived from ethylene inthe copolymer.
 7. The copolymer of claim 1 having a melting point (Tm)in ° C., as measured by DSC, that satisfies the relation:Tm>3.4×E−160 where E is the weight % of units derived from ethylene inthe copolymer.
 8. The copolymer of claim 1 having a melting point (Tm)in ° C., as measured by DSC, that satisfies the relation:Tm>3.4×E−90 where E is the weight % of units derived from ethylene inthe copolymer.
 9. The copolymer of claim 1 containing no more than 10ppm of Zn.
 10. An ethylene copolymer comprising 70 wt. % to 85 wt. % ofunits derived from ethylene and at least 12 wt. % of units derived fromat least one α-olefin having 3 to 20 carbon atoms, wherein the copolymerhas the following properties: (a) a weight-average molecular weight(Mw), as measured by GPC, in the range of about 50,000 to about 200,000g/mol; (b) a melting point (Tm), as measured by DSC, of at least 100°C.; (c) a ratio of Mw/Mn of about 1.5 to about 3.5; (d) a content ofGroup 4 metals of no more than 25 ppm; and (e) a ratio of wt ppm Group 4metals/wt ppm Group 5 metals of at least
 3. 11. The copolymer of claim10 having a melting point (Tm), as measured by DSC, of at least 110° C.12. The copolymer of claim 10 wherein said at least one α-olefin isselected from propylene, butene, hexene and octene.
 13. The copolymer ofclaim 10 wherein said at least one α-olefin comprises propylene.
 14. Thecopolymer of claim 10 containing no more than 25 ppm of Zn.
 15. Aprocess of producing an ethylene copolymer, the process comprisingcontacting a monomer mixture comprising 40 wt. % to 70 wt. % of ethyleneand at least 30 wt. % of at least one α-olefin having 3 to 20 carbonatoms under polymerizations conditions with a catalyst compositioncomprising a bridged bis-indenyl complex of a transition metal toproduce a copolymer having the following properties: (a) aweight-average molecular weight (Mw), as measured by GPC, in the rangeof about 50,000 to about 200,000 g/mol; (b) a melting point (Tm) in °C., as measured by DSC, that satisfies the relation:Tm>3.4×E−180 where E is the weight % of units derived from ethylene inthe copolymer; (c) a ratio of Mw/Mn of about 1.5 to about 3.5; (d) acontent of Group 4 metals of no more than 25 ppm; and (e) a ratio of wtppm Group 4 metals/wt ppm Group 5 metals of at least
 3. 16. The processof claim 15 wherein the bridged bis-indenyl complex comprises adialkylsilyl bridging group.
 17. The process of claim 15 wherein thetransition metal comprises hafnium and/or zirconium.
 18. The process ofclaim 15 wherein the catalyst composition comprisesdimethylsilylbisindenyl hafnium dimethyl.
 19. The process of claim 15wherein the catalyst composition comprises a fluoroarylborate activator.20. The process of claim 15 wherein the catalyst composition comprises aperfluorophenylborate activator.
 21. The process of claim 15 wherein thecatalyst composition comprises rac-dimethylsilylbisindenyl hafniumdimethyl and a trimethylammonium tetrakis-pentafluorophenylborateactivator.
 22. A process of producing an ethylene copolymer, the processcomprising contacting a monomer mixture comprising 70 wt. % to 85 wt. %of ethylene and at least 12 wt. % of at least one α-olefin having 3 to20 carbon atoms under polymerizations conditions with a catalystcomposition comprising a bridged bis-indenyl complex of a transitionmetal to produce a copolymer having the following properties: (a) aweight-average molecular weight (Mw), as measured by GPC, in the rangeof about 50,000 to about 200,000 g/mol; (b) a melting point (Tm), asmeasured by DSC, of at least 100° C.; (c) a ratio of Mw/Mn of about 1.5to about 3.5; (d) a content of Group 4 metals of no more than 25 ppm;and (e) a ratio of wt ppm Group 4 metals/wt ppm Group 5 metals of atleast
 3. 23. The process of claim 22 wherein the catalyst compositioncomprises a perfluorophenylborate activator.
 24. The process of claim 22wherein the catalyst composition comprises a rac-dimethylsilylbisindenylhafnium dimethyl and a trimethylammoniumtetrakis-pentafluorophenylborate activator.
 25. A lubricating oilcomposition comprising (a) a lubricating oil base and (b) ethylenecopolymer comprising 40 wt. % to 70 wt. % of units derived from ethyleneand at least 30 wt. % of units derived from at least one α-olefin having3 to 20 carbon atoms, wherein the copolymer has the followingproperties: (a) a weight-average molecular weight (Mw), as measured byGPC, in the range of about 50,000 to about 200,000 g/mol; (b) a meltingpoint (TM) in ° C., as measured by DSC, that satisfies the relation:Tm>3.4×E−180